When the Red Sox signed Ryan Roberts to help man third base in the absence of Will Middlebrooks, they sat on the cusp of a stretch where they’d face five left-handed starters in a 10-day span. Though the Sox went 4-1 in those contests, that was hardly a reflection of Roberts’ performance. The 33-year-old was just 2-for-19 with two singles and three walks, good for a .105/.227/.105 line, and with the Sox now arriving at a stage where they’ll face primarily right-handed starters, and with Middlebrooks moving closer to a return from the DL, the team elected to designate Roberts for assignment.

In his place, the team called up Brock Holt from Triple-A Pawtucket. Holt, who spent one day on the big league roster when Middlebrooks first landed on the DL, has been on a tear for the PawSox, hitting .380/.446/.600 with eight extra-base hits, five walks and three strikeouts in 56 plate appearances. The Sox immediately put Holt in Friday’s lineup.

“We felt like we needed to try to create a little bit of a jump-start to the offense. With the designation of Ryan, we got another lefthanded hitter here in Brock Holt,” said Sox manager John Farrell. “We’ve come through a stretch with seven lefthanded starters against us out of the past 10, and we’re kind of reversing that right now, going against primarily righthanders. We felt like we needed to try a different combination to attempt to spark that bottom third of the order.

“[Holt has] clearly earned the promotion here,” added Farrell. “When he was sent out, even after just one day of being here with the big-league club, he was initially disappointed, but he’s channeled that the right way and gone down and played very well on the left side of the infield.”

As for Roberts, Farrell suggested that he didn’t appear to be in sync after spending about 10 days at home following his release from the Cubs at the end of spring training. The Sox hope that the versatile Roberts will clear waivers and accept an assignment to Triple-A Pawtucket.

“We certainly want him to remain in the organization,” said Farrell. “We feel like he needs at-bats to get things going a little bit.”

As for Middlebrooks, he rejoined the Red Sox (he’d been sent home early from Chicago while struggling with the flu) and resumed baseball activities, including batting practice. Given the relatively limited time of his absence with the flu, the Sox are hopeful that Middlebrooks — who is eligible to come off the D.L. on Monday, but won’t be ready to do so at that point — will be ready to start a minor league rehab assignment in relatively short order.

“I don’t think [the flu] is going to delay Will in his eventual rehab assignment, which we’re still hopefully targeting sometime the middle of next week,” said Farrell.

— Shane Victorino remains on track to start his rehab assignment with Triple-A Pawtucket on Saturday, followed by games on Monday and Tuesday, at which point he’ll be re-evaluated for potential activation from the disabled list.

— Koji Uehara came through his return to the mound on Thursday (a scoreless ninth for the save against the White Sox), and Farrell said he’ll be available again on Friday.

— Farrell said that the fact that David Ross has caught all but one of Jon Lester‘s starts was a mere coincidence, a reflection of the fact that the Sox have faced left-handed starters on the day when Lester takes the hill. In the three games when Ross and Lester have been paired, the first was a day game after a night game against the Brewers, the second featured left-hander CC Sabathia on the mound for the Yankees and the third had Chris Sale on the mound for the White Sox.

“I wouldn’t look too deep into Lester and Ross hooking up all the time. It’s just been lefthanded starters the last two, three times out that they have connected,” said Farrell. “Going forward, we’ll look at the best matchup for who’s behind the plate.”